Based on the hourly rainfall data of 2066 automatic weather stations and rainstorm disaster information in Chongqing from 2011 to 2021, the rainstorm process slide sampling and percentile method are used to determine the rainstorm warning signal standards for counties and the disaster risk warning grades for the whole city， which is expected to provide some references for Chongqing local departments to initiate rainstorm emergency response. The main conclusions are as follows. A total of 5363 rainstorm processes occurred in 34 counties with meteorological services in Chongqing, with an average of 14.3 times per year in each county. The time lengths of 1, 3 and 12 h are selected as the reference durations for issuing rainstorm process warning signals. Rainstorm warning signal (blue, yellow, orange, and red) standard thresholds of different durations are obtained by sorting the rainfall data in ascending order to the nearest value within the 30%-50%, 70%-80%, 90%-95%, and 99%-99.9% percentile ranges, and they are 1 h-30-50-70-100 mm, 3 h-50-70-100-150 mm and 12 h-70-100-150-250 mm. The probability of disaster indicated by different warning signals increases with signal level and duration. Warning signals of blue, yellow, orange and red for each county have an average of 5.4, 4.0, 1.3 and 0.18 times per year according to the highest warning level of different durations, and the disaster probability of different warning signals are 30%, 60%, 85%, and 95% respectively. A total of 114 regional rainstorm processes occurred in the whole city of Chongqing from 2011 to 2021, and rainstorm disaster risk warning levels determined by the number of possible disaster counties have an average of 5.3 (Ⅳ), 3.1 (Ⅲ), 1.6 (Ⅱ) and 0.1 (Ⅰ) times per year. This is basically consistent with the frequency of counties and conforms to the regularity of warning releases.